Fix registration of internal readonly child classes (#15459)

Currently, internal classes are registered with the following code:

INIT_CLASS_ENTRY(ce, "InternalClass", class_InternalClass_methods);
class_entry = zend_register_internal_class_ex(&ce, NULL);
class_entry->ce_flags |= ...;

This has worked well so far, except if InternalClass is readonly. It is because some inheritance checks are run by zend_register_internal_class_ex before ZEND_ACC_READONLY_CLASS is added to ce_flags.

The issue is fixed by adding a zend_register_internal_class_with_flags() zend API function that stubs can use from now on. This function makes sure to add the flags before running any checks. Since the new API is not available in lower PHP versions, gen_stub.php has to keep support for the existing API for PHP 8.3 and below.

Author: kocsismate

Zend/zend_API.c

@@ -3493,9 +3493,16 @@ static zend_class_entry *do_register_internal_class(zend_class_entry *orig_class
  */
 ZEND_API zend_class_entry *zend_register_internal_class_ex(zend_class_entry *class_entry, zend_class_entry *parent_ce) /* {{{ */
 {
-	zend_class_entry *register_class;
+	return zend_register_internal_class_with_flags(class_entry, parent_ce, 0);
+}
+/* }}} */
 
-	register_class = zend_register_internal_class(class_entry);
+ZEND_API zend_class_entry *zend_register_internal_class_with_flags(
+	zend_class_entry *class_entry,
+	zend_class_entry *parent_ce,
+	uint32_t ce_flags
+) {
+	zend_class_entry *register_class = do_register_internal_class(class_entry, ce_flags);
 
 	if (parent_ce) {
 		zend_do_inheritance(register_class, parent_ce);
@@ -3504,7 +3511,6 @@ ZEND_API zend_class_entry *zend_register_internal_class_ex(zend_class_entry *cla
 
 	return register_class;
 }
-/* }}} */
 
 ZEND_API void zend_class_implements(zend_class_entry *class_entry, int num_interfaces, ...) /* {{{ */
 {

Zend/zend_API.h

@@ -390,6 +390,7 @@ ZEND_API void zend_add_magic_method(zend_class_entry *ce, zend_function *fptr, z
 
 ZEND_API zend_class_entry *zend_register_internal_class(zend_class_entry *class_entry);
 ZEND_API zend_class_entry *zend_register_internal_class_ex(zend_class_entry *class_entry, zend_class_entry *parent_ce);
+ZEND_API zend_class_entry *zend_register_internal_class_with_flags(zend_class_entry *class_entry, zend_class_entry *parent_ce, uint32_t flags);
 ZEND_API zend_class_entry *zend_register_internal_interface(zend_class_entry *orig_class_entry);
 ZEND_API void zend_class_implements(zend_class_entry *class_entry, int num_interfaces, ...);
 

Zend/zend_attributes_arginfo.h

@@ -3274,11 +3274,18 @@ public function getRegistration(array $allConstInfos): string
         $code .= "static zend_class_entry *register_class_$escapedName(" . (empty($params) ? "void" : implode(", ", $params)) . ")\n";
 
         $code .= "{\n";
+
+        $flagCodes = generateVersionDependentFlagCode("%s", $this->getFlagsByPhpVersion(), $this->phpVersionIdMinimumCompatibility);
+        $flags = implode("", $flagCodes);
+
         if ($this->type === "enum") {
             $name = addslashes((string) $this->name);
             $backingType = $this->enumBackingType
                 ? $this->enumBackingType->toTypeCode() : "IS_UNDEF";
             $code .= "\tzend_class_entry *class_entry = zend_register_internal_enum(\"$name\", $backingType, class_{$escapedName}_methods);\n";
+            if ($flags !== "") {
+                $code .= "\tclass_entry->ce_flags |= $flags\n";
+            }
         } else {
             $code .= "\tzend_class_entry ce, *class_entry;\n\n";
             if (count($this->name->getParts()) > 1) {
@@ -3291,15 +3298,29 @@ public function getRegistration(array $allConstInfos): string
             }
 
             if ($this->type === "class" || $this->type === "trait") {
-                $code .= "\tclass_entry = zend_register_internal_class_ex(&ce, " . (isset($this->extends[0]) ? "class_entry_" . str_replace("\\", "_", $this->extends[0]->toString()) : "NULL") . ");\n";
+                if (!$php84MinimumCompatibility) {
+                    $code .= "#if (PHP_VERSION_ID >= " . PHP_84_VERSION_ID . ")\n";
+                }
+
+                $code .= "\tclass_entry = zend_register_internal_class_with_flags(&ce, " . (isset($this->extends[0]) ? "class_entry_" . str_replace("\\", "_", $this->extends[0]->toString()) : "NULL") . ", " . ($flags ?: 0) . ");\n";
+
+                if (!$php84MinimumCompatibility) {
+                    $code .= "#else\n";
+
+                    $code .= "\tclass_entry = zend_register_internal_class_ex(&ce, " . (isset($this->extends[0]) ? "class_entry_" . str_replace("\\", "_", $this->extends[0]->toString()) : "NULL") . ");\n";
+                    if ($flags !== "") {
+                        $code .= "\tclass_entry->ce_flags |= $flags;\n";
+                    }
+                    $code .= "#endif\n";
+                }
             } else {
                 $code .= "\tclass_entry = zend_register_internal_interface(&ce);\n";
+                if ($flags !== "") {
+                    $code .= "\tclass_entry->ce_flags |= $flags\n";
+                }
             }
         }
 
-        $flagCodes = generateVersionDependentFlagCode("\tclass_entry->ce_flags |= %s;\n", $this->getFlagsByPhpVersion(), $this->phpVersionIdMinimumCompatibility);
-        $code .= implode("", $flagCodes);
-
         if ($this->exposedDocComment) {
             if (!$php84MinimumCompatibility) {
                 $code .= "#if (PHP_VERSION_ID >= " . PHP_84_VERSION_ID . ")\n";